Elongate tubular devices, such as diagnostic or treatment catheters or sheaths may be provided for introduction into a patient's body, e.g., the patient's vasculature or other body lumens. For example, a catheter may have a distal portion configured to be introduced into a body lumen and advanced to one or more desired locations within the patient's body by manipulating a proximal end of the catheter.
To facilitate introduction of such a catheter, one or more wires, cables, or other steering elements may be provided within the catheter, e.g., that are coupled to the distal portion and may be pulled or advanced from the proximal end to deflect the distal portion. For example, a steering element may be provided that is intended to deflect the distal portion within a predetermined plane and/or into a desired curved shape.
Pull wires are a common way to impart deflection ability to such a catheter. However, there are a number of drawbacks associated with such pull wires. For example, a pull wire occupies a significant amount of space within the catheter body. In addition, a pull wire frequently needs to be reinforced, e.g., on the inside and outside of the braid or other reinforcement of the catheter, e.g., to prevent “pull through” when the pull wire is actuated by pushing or pulling, i.e., the resulting bending moment may cause the pull wire to separate layers of or tear at least partially through the wall of catheter, potentially splitting the catheter. Further, a pull wire can make the torque properties of the catheter non-homogenous, making it difficult or impossible to torque the catheter when the pull wire is actuated, e.g., within a tortuous pathway. Further, auxiliary lumens, in particular those located in the wall of a large bore sheath, are difficult to manufacture with consistency due to difficulties with alignment, hand assembly, and the like.
In addition, catheters, sheaths, or other tubular devices may include one or more wires or conductors therein, e.g., for operating one or more elements on a distal portion of the device. Incorporating electrically conductive wires or elements into thin walled tubular devices, such as deflectable sheaths, may be challenging. For example, one or more wires may be provided inside the wall of a catheter that extend longitudinally, but such wires may add undesired profile to the device. Even more problematic, when a catheter flexes or torques during standard catheter use, the catheter wall, of necessity, must accommodate the path length differences induced by the different arc lengths of the inside and outside bend radii of the catheter, which leads to both compression and elongation of the wall. During compression, the wire(s) may buckle and subsequently fatigue and/or wear their insulation, while during extension, the wire(s) and any associated insulation may not be able to handle the required elongation without compromising the wire(s) or their insulation. In the case of a wire conductor, the conductor may neck after bending, which may create hot spots, impedance problems, and the like or eventually fatigue and break, e.g., after bending the catheter multiple times as it is manipulated within a patient's body. Changes to electrical properties in any way may be problematic as the conductors are used for many purposes including impedance measurements, high current delivery (e.g., RF ablation), high voltage delivery (e.g., defibrillation), simple tissue voltage/timing measurements, and the like.
Accordingly, there is a need for improved catheters, sheaths, and other tubular devices and methods of their manufacture.